Layered Battery Electrode Structure for Stress-Resilient Conductivity
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Solution Overview
Problem
Lithium-ion batteries face performance deterioration due to uneven expansion and contraction of active material layers, leading to decreased ion and electron conductivity and potential internal short circuits, which compromises electrode performance and safety.
Innovation Solution
An electrode structure with a collector and active material mixture layers, where the first and second mixture layers have deformed and non-deformed particles with a flat surface, allowing for discontinuous contact points that absorb stress and maintain conductivity, preventing synchronization of expansion and contraction and thus reducing the risk of breakage and buckling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the density of active materials is increased to increase battery capacity, then the capacity increases, but the contact points between active material particles decrease and conductivity deteriorates
Solution Approach 1:
The electrode is divided into multiple layers with different active material particles (first, second, and third particles with different average diameters). This segmentation allows each layer to contribute differently to capacity while maintaining overall conductivity through the gradient structure, resolving the contradiction between increasing material density and maintaining contact points.
Solution Approach 2:
Different regions of the electrode have different particle size distributions. The first particles (larger) provide structural stability and maintain contact points, while second and third particles (smaller) fill gaps and increase density. This local quality variation allows simultaneous optimization of both capacity and conductivity.
2Quantity of substance
If the density of active materials is increased, then battery capacity increases, but internal stress increases causing electrode breakage or buckling
Solution Approach 1:
The electrode structure is segmented into multiple layers with gradation in particle sizes. This segmentation distributes the expansion and contraction stresses across different layers during charging/discharging cycles, preventing concentration of internal stress that would lead to breakage or buckling, while still achieving high capacity through increased material density.
Solution Approach 2:
The particle size parameter is changed gradually across different layers (first particles larger than second, second larger than third). This parameter gradient allows progressive accommodation of volume changes during electrochemical reactions, reducing internal stress and maintaining electrode integrity while maximizing active material content.
3Use of energy by moving object
If active material particles expand and contract during charging/discharging, then electrochemical reactions occur, but contact points decrease and performance deteriorates
Solution Approach 1:
The electrode is segmented into multiple layers with different particle sizes that can expand and contract independently. The larger first particles maintain structural framework and contact points, while smaller second and third particles fill interstitial spaces. This segmentation allows each layer to undergo volume changes without losing overall contact connectivity, maintaining both electrochemical activity and reliability.
Solution Approach 2:
The electrode uses a composite structure with multiple types of particles (first, second, and third particles with different sizes and properties). This composite material approach creates a hierarchical structure where larger particles provide mechanical stability and contact pathways, while smaller particles enhance surface area and reaction sites, allowing simultaneous maintenance of contact points and electrochemical activity during expansion/contraction cycles.
Data Source
AI summary
An electrode includes a collector, and an active material mixture layer located on the collector and containing first particles, second particles, first active material particles, and second active material particles. The active material mixture layer includes a first mixture layer located on the collector and containing the first particles and the first active material particles, and a second mixture layer located on the first mixture layer and containing the second particles and the second active material particles. The active material mixture layer has a boundary in which the first active material particles and the second active material particles are in contact with each other in a discontinuous state at least in part, in a cross-sectional view of the electrode.